Long Term Evolution (LTE) Service providers that provide Voice over LTE (VoLTE) wish to offer the VoLTE service to their subscribers not only in the subscribers' home country but also in a visited network. For example, when the subscriber roams into a visited network that does not offer LTE coverage, the subscriber may fall back to a circuit-switched (CS) technology afforded by a second generation (2G) network or a third generation (3G) network.